The present invention relates to electrode caps particularly suited for use in electroencephalographic apparatus and more particularly to an improved electrode assembly and method of attaching electrode assemblies to an elastic cap.
References known to the present Applicant and believed to be relevant to the invention include: U.S. Pat. No. 3,998,213 issued to Price on Dec. 21, 1976; U.S. Pat. No. 4,085,739 issued to the present applicant on Apr. 25, 1978; and the publication entitled "The Promise Technology Holds for the Future of EEG Technology" by Frost, Jr., found at Pages 65 to 75 of Volume 12, No. 2 (1972) of The American Journal of EEG Technology. The Price patent teaches an elastic cap carrying electrodes in the international 10/20 system for use with EEG recorders. The elastic portion of the Price device comprises a series of elastic straps held together by electrode holders. The above-referenced Frost article teaches a similar cap assembled from essentially continuous stretchable fabric with a plurality of electrodes attached to the inner surface of the elastic cap. This cap is held on the patient's head by a chin strap. My above-referenced patent teaches an electrode harness arrangement by which any type of EEG cap can be held on the patient's head without inducing muscle reactions in the patient which can interfere with the proper recording of electroencephalograms.
As shown by the above references, elastic electrode caps for use with EEG's are well known and have been well accepted. Such caps greatly reduce the time required for proper application of the EEG electrodes to a patient's head by a technician. The elastic cap arrangements also reduce the possibility of movement of the electrode or loss of electrical contact during the taking of the electroencephalogram. However, as shown by these references, the electrode assemblies used in such caps have been fairly complicated.
While these elastic EEG caps have become quite popular, they remain quite expensive due to the complexity of proper assembly. In a typical fabrication process, an elastic cap is first manufactured from three or more pieces of elastic material. A pattern is then laid onto the cap and proper locations of electrodes, for example, the international 10/20 system arrangement, are marked onto the cap. A metal electrode is then typically pressed into a rubber grommet which is positioned on one side of the cap at one of the marked locations while cement is applied to the fabric. A fiber washer is usually placed on the opposite side of the fabric so that the entire assembly may then be clamped until the cement hardens to hold the electrode assembly in place. Since typically seventeen or more electrodes must be attached to the cap, it can be seen that a considerable amount of time is required to completely assemble such an electrode cap.